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module ActionView
# There's also a convenience method for rendering sub templates within the current controller that depends on a single object
# (we call this kind of sub templates for partials). It relies on the fact that partials should follow the naming convention of being
# prefixed with an underscore -- as to separate them from regular templates that could be rendered on their own.
#
# In a template for Advertiser#account:
#
# <%= render :partial => "account" %>
#
# This would render "advertiser/_account.erb" and pass the instance variable @account in as a local variable +account+ to
# the template for display.
#
# In another template for Advertiser#buy, we could have:
#
# <%= render :partial => "account", :locals => { :account => @buyer } %>
#
# <% for ad in @advertisements %>
# <%= render :partial => "ad", :locals => { :ad => ad } %>
# <% end %>
#
# This would first render "advertiser/_account.erb" with @buyer passed in as the local variable +account+, then render
# "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display.
#
# == Rendering a collection of partials
#
# The example of partial use describes a familiar pattern where a template needs to iterate over an array and render a sub
# template for each of the elements. This pattern has been implemented as a single method that accepts an array and renders
# a partial by the same name as the elements contained within. So the three-lined example in "Using partials" can be rewritten
# with a single line:
#
# <%= render :partial => "ad", :collection => @advertisements %>
#
# This will render "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display. An iteration counter
# will automatically be made available to the template with a name of the form +partial_name_counter+. In the case of the
# example above, the template would be fed +ad_counter+.
#
# NOTE: Due to backwards compatibility concerns, the collection can't be one of hashes. Normally you'd also just keep domain objects,
# like Active Records, in there.
#
# == Rendering shared partials
#
# Two controllers can share a set of partials and render them like this:
#
# <%= render :partial => "advertisement/ad", :locals => { :ad => @advertisement } %>
#
# This will render the partial "advertisement/_ad.erb" regardless of which controller this is being called from.
#
# == Rendering partials with layouts
#
# Partials can have their own layouts applied to them. These layouts are different than the ones that are specified globally
# for the entire action, but they work in a similar fashion. Imagine a list with two types of users:
#
# <!-- app/views/users/index.html.erb -->
# Here's the administrator:
# <%= render :partial => "user", :layout => "administrator", :locals => { :user => administrator } %>
#
# Here's the editor:
# <%= render :partial => "user", :layout => "editor", :locals => { :user => editor } %>
#
# <!-- app/views/users/_user.html.erb -->
# Name: <%= user.name %>
#
# <!-- app/views/users/_administrator.html.erb -->
# <div id="administrator">
# Budget: $<%= user.budget %>
# <%= yield %>
# </div>
#
# <!-- app/views/users/_editor.html.erb -->
# <div id="editor">
# Deadline: $<%= user.deadline %>
# <%= yield %>
# </div>
#
# ...this will return:
#
# Here's the administrator:
# <div id="administrator">
# Budget: $<%= user.budget %>
# Name: <%= user.name %>
# </div>
#
# Here's the editor:
# <div id="editor">
# Deadline: $<%= user.deadline %>
# Name: <%= user.name %>
# </div>
#
# You can also apply a layout to a block within any template:
#
# <!-- app/views/users/_chief.html.erb -->
# <% render(:layout => "administrator", :locals => { :user => chief }) do %>
# Title: <%= chief.title %>
# <% end %>
#
# ...this will return:
#
# <div id="administrator">
# Budget: $<%= user.budget %>
# Title: <%= chief.name %>
# </div>
#
# As you can see, the :locals hash is shared between both the partial and its layout.
module Partials
private
def render_partial(partial_path, object_assigns = nil, local_assigns = nil) #:nodoc:
case partial_path
when String, Symbol, NilClass
path, partial_name = partial_pieces(partial_path)
object = extracting_object(partial_name, object_assigns)
local_assigns = local_assigns ? local_assigns.clone : {}
add_counter_to_local_assigns!(partial_name, local_assigns)
add_object_to_local_assigns!(partial_name, local_assigns, object)
if logger
ActionController::Base.benchmark("Rendered #{path}/_#{partial_name}", Logger::DEBUG, false) do
render("#{path}/_#{partial_name}", local_assigns)
end
else
render("#{path}/_#{partial_name}", local_assigns)
end
when Array, ActiveRecord::Associations::AssociationCollection
if partial_path.any?
path = ActionController::RecordIdentifier.partial_path(partial_path.first)
collection = partial_path
render_partial_collection(path, collection, nil, object_assigns.value)
else
""
end
else
render_partial(
ActionController::RecordIdentifier.partial_path(partial_path),
object_assigns, local_assigns)
end
end
def render_partial_collection(partial_name, collection, partial_spacer_template = nil, local_assigns = nil) #:nodoc:
collection_of_partials = Array.new
counter_name = partial_counter_name(partial_name)
local_assigns = local_assigns ? local_assigns.clone : {}
collection.each_with_index do |element, counter|
local_assigns[counter_name] = counter
collection_of_partials.push(render_partial(partial_name, element, local_assigns))
end
return " " if collection_of_partials.empty?
if partial_spacer_template
spacer_path, spacer_name = partial_pieces(partial_spacer_template)
collection_of_partials.join(render("#{spacer_path}/_#{spacer_name}"))
else
collection_of_partials.join
end
end
alias_method :render_collection_of_partials, :render_partial_collection
def partial_pieces(partial_path)
if partial_path.include?('/')
return File.dirname(partial_path), File.basename(partial_path)
else
return controller.class.controller_path, partial_path
end
end
def partial_counter_name(partial_name)
"#{partial_variable_name(partial_name)}_counter".intern
end
def partial_variable_name(partial_name)
partial_name.split('/').last.split('.').first.intern
end
def extracting_object(partial_name, object_assigns)
variable_name = partial_variable_name(partial_name)
if object_assigns.nil?
controller.instance_variable_get("@#{variable_name}")
else
object_assigns
end
end
def add_counter_to_local_assigns!(partial_name, local_assigns)
counter_name = partial_counter_name(partial_name)
local_assigns[counter_name] = 1 unless local_assigns.has_key?(counter_name)
end
def add_object_to_local_assigns!(partial_name, local_assigns, object)
variable_name = partial_variable_name(partial_name)
local_assigns[variable_name] ||=
if object.is_a?(ActionView::Base::ObjectWrapper)
object.value
else
object
end || controller.instance_variable_get("@#{variable_name}")
end
end
end
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